A relay is a switch. In use, for example, a relay is connected at one end to a source and at another end to a load. When switched on, the relay is closed and connects the source to the load. In this case, electrical energy (e.g., current) may flow from the source through the relay to the load. When switched off, the relay is opened and disconnects the source from the load. In this case, no current may flow from the source to the load via the relay. This is because the source and the load are electrically isolated from one another by the relay.
Current flowing through a relay generates heat. Some of the heat transfers away from the relay. The heat dissipates through the relay system until thermal equilibrium is achieved. A problem occurs when the thermal equilibrium temperature is higher than what the relay system components can handle. In this case, the relay can malfunction and/or melt. Remedies include limiting the current flow such that heat generates slower than can be transferred away from the relay and/or employing a physically larger relay such that more heat can be transferred away from the relay. Both remedies have undesired attributes.